A contractual clause providing for an optional technical appraisal procedure for the ascertainment and quantification of damage, with a majority decision by a panel of experts appointed by the parties, does not constitute an arbitration agreement, whether formal or contractual, but rather a contractual expert appraisal, with the result that art. 810 of the code of civil procedure does not apply and the party unable to activate the procedure by mutual agreement retains the right to bring proceedings before the ordinary courts.